Re: qsort again (was Re: [PERFORM] Strange Create Index

Mark Lewis <mark.lewis@mir3.com>

From: Mark Lewis <mark.lewis@mir3.com>
To: Greg Stark <gsstark@mit.edu>
Cc: Markus Schaber <schabi@logix-tt.com>, pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
Date: 2006-02-16T23:23:09Z
Lists: pgsql-hackers, pgsql-performance
On Thu, 2006-02-16 at 17:51 -0500, Greg Stark wrote:
> > > Data types which could probably provide a useful function for f would be
> > > int2, int4, oid, and possibly int8 and text (at least for SQL_ASCII).
> 
> How exactly do you imagine doing this for text?
> 
> I could see doing it for char(n)/varchar(n) where n<=4 in SQL_ASCII though.


In SQL_ASCII, just take the first 4 characters (or 8, if using a 64-bit
sortKey as elsewhere suggested).  The sorting key doesn't need to be a
one-to-one mapping.

-- Mark Lewis